Compressor



May 4, 1965 K. H. RHODES 3,181,779

COMPRES S OR Filed Sept. 6, 1962 2 Sheets-Sheet 1 MW'QVM K. H. RHODES May 4, 1965 COMPRESSOR 2 Sheets-Sheet 2 Filed Sept. 6, 1962 d -2 fw INVENTOR. /ffz'cilf /7. 777566765.

VJLQ( United States Patent() "ce 3,181,779 COMPRESSOR Keith H. Rhodes, Racine, Wis., assignor to Walker Manufacturing Company, Racine, Wis., a corporation of Delaware Filed Sept. 6, 1962, Ser. No. 221,729 1 Claim. (Cl. 230-172) This invention relates generally to air compressors and more particularly to an improved positive displacementV air compressor. Y

Conventional positive displacement air compressors generally comprise a piston that is driven lby a crankshaft through an articulated connecting rod. The piston is movable in translation within a complementary cylinder, eccentricity of the crankshaft being accommodated by articulation of the connecting rod.

The air compressor of the instant invention features a one-piece piston and connecting rod that is molded from nylon or similar material, thereby eliminating the conventional connecting rod and wrist pin, as well as the problems attendant to manufacture and assembly of the rod, wrist pin and piston.

Accordingly, one object of the instant invention is an improved air compressor.

Another object of the instant invention is an air compressor having a one-piece piston and connecting rod.

Another object of the instant invention is an air compressor having a piston molded from nylon or similar material.

Another object is an air compressor that eliminates the conventional wrist pin and connecting rod assembly.

Another object is an improved balancing system for an air compressor.

Other objects and advantages of the instant invention will be apparent in the following specifications, claims and drawings, wherein:

FIGURE 1 is a side view of an air compressor in accordance with an exemplary embodiment of the instant invention shown in operativeassociation with a conventional electric motor;

FIG. 2 is a cross sectional view taken substantially along the line 2-2 of FIGURE l;

FIG. 3 is a cross sectional view taken substantially along the line 3 3 of FIG. 2;

FIG. 4 Iis a view taken substantially in the direction of the arrow 4 in FIG. 2 with the crankshaft rotated approximately 90;

FIG. 5 is a cross sectional view similar to FIG. 2 of a modified form of the air compressor of then instant invention; and

FIG. 6 is a cross sectional view taken substantially along the line 6-6 of FIG. 5.

As best seen in FIGURE l of the drawings, an air compressor 10, in accordance with an exemplary embodiment of the instant invention is shown inoperative association with an electric motor 12. The air compressor 10 is secured to the motor 12 as by a pair of mounting bolts 14 and 16 (FIG. 2) having complementary nuts 18 and 20, respectively.

As best seen in FIG. 2 of the drawings, the air compressor 10 comprises a crank housing 20, preferably a steel stamping, having a pair of radially extending anges 22 and 24 with apertures 26 and 28 for the acceptance of the mounting bolts 14 and 16 on the motor 12, respec` tively. The housing 20 is of tubular construction having an inside diameter complementary to a bearing housing 30 of the motor 12 for the acceptance thereof in slidable press t relationship.

The crank housing 20 has an inner end plate 32 with an outer peripheral rib portion 34 of a diameter complementary to the inside diameter of the housing 20 -so as to be acceptable therein in press fit relationship. The end cap 32 has an aperture 36'therein for the acceptance of an output shaft 38 of the motor 12. The housing 20 also has an annular outer end'cap 40l with a peripheral rib 42 thereon of a diameter complementary to the inside diameter of the housing 20 so as to be acceptable therein to press fit relationship. The outer end cap 40 is of annular construction for the acceptance of a complementary circular valve assembly generally designated by the numeral 50, the details of which will be described hereinafter.

A cylinder 60, of circular cross section, is secured within a complementary aperture 62 in the housing 20, as by brazing. The cylinder 60 has an inside diameter similar to the inside diameter of the annular end cap 40 for the acceptance of a valve assembly 50 of identical construction to the valve assembly 50 in the end cap 40 of the housing 20.

A piston 70, molded from, for example, nylon or a uorocarbon, functions as a combined piston, wrist pin and connecting rod. A cylinder-contacting peripheral surface 72 on the piston 70 is dened by what may be termed a section of a sphere. Thus, whatever the angularity of the piston 70'relative to the central axis of the cylinder 60, the surface 72 is maintained in sealing line contact with the cylinder 60. An end portion 74.0f the piston 70 has a bore 76 therein for the acceptance of a crank pin 78. It is to be noted that the crank pin 78 is `secured directly to the output shaft 38 of the motor 12 by a machine screw 80, a threaded end portion 82 of which is accepted in a complementary threaded bore 84 in the crank pin 78. It is also to -be noted that a head portion 86 of the machine screw 80 is of relatively large diameter and axial dimension, thereby to function, in combination with a counterweight cup 90, as a counterweight for the crank pin 78, thereby to statically balance Ithevcrank pin 78 and the piston assembly 70.

As best seen in FIGS. 2 and 3, the Valve assembly 50 comprises a tubular valve housing having a pair of diametrically related anges 102 and 104 thereon to facilitate attachment of the housing V100 to an annular valve plate 106. The valve plate 106 is retained on the cylinder 60 by a plurality of folded tabs 107, 108 and 109 thereon.

A sleeve 110 is disposed interiorly of the valve housing 100 to function as a stop for a generally rectangular disc Vvalve 112. The disc valve 112 is seated alternatively against the valve disc 106 to close a central aperture 113 therein and against an annular end portion 1140i the sleeve 110, `as will be described. The sleeve 1'10 has a plurality of circumferentially spaced apertures 116 therein for the passage of air outwardly of the valve housing 100 when the valve 112 is `seated against the seat 114 on the sleeve 110.

An annular ilappervalve 120 having a central aperture 121 is retained against the valve plate 106 by a pair of rivets 122 and 124 that extend through complementary spacers 126 and 128, respectively. The liapper valve 120 normally closes a pair of apertures 130 and 132 (FIGS. 1 and 3) in the valve plate 106 to preclude the passage of air outwardly therethrough.

Upon movement of the piston 70 downwardly, as seen in FIG. 2 of the drawings, the flapper valve 120 dellects downwardly, as lseen in FIG. 3 of the drawings, due to a pressure differential created thereacross, Whereuponair is admitted through the apertures 130 and 132 in the valve plate 106. i

Upon movement of the piston 70 upwardly within the cylinder 60, as seen in FIG. 2 of the drawings, the tlapper valve 120 is biased against the valve plate 106 bythe air pressure differential thereacross and by its ownfresilience, sealing the apertures 130 land 132 in the valve plate 106.

3,181,779 s Patented May 4, 1965 I ensure it l The disc valve 112, is biased against the edge portion 114 on the sleeve 11G, thereby permitting discharge of air under pressure outwardly through the central apertures 121 and 113 in the tlapper valve 12) and valve plate 106,k

respectively, around the disc valve 112, through the apertures 116 in the sleeve 110 and outwardly of the valve housing 100.

lt should be apparent that the use of valve assemblies 50 on opposite sides of the piston 70 results in a double action air compression in that air is compressed upon movement of the piston 70 in either direction.

As seen in FIG. 5 of the drawings, a modied air compressor 2li@ comprises a crank housing 202 having radially extending anges 204 and 206 to facilitate attachment of the air compressor 260 to the-motor 12. A cylinder 210 is secured to the housing 202 as by brazing. The cylinder 210 is provided with a pair of valve assemblies 50 similar to t-he valve assemblies discussed hereinbefore, which are supported in axial alignment with the central axis of the cylinder 210 and normally to the central axis 38 or" the motor 12.

From the foregoing description, it should be apparent that the air compressors 10 and 20) feature a piston which is molded of nylon or similar material. The piston is unique in that it combines the customary piston, Wrist pin and connecting rod of conventional piston-type compressors heretofore known and used. The cylinder-contacting surface of the piston comprises a center section of a sphere. Thus, sealing line contact is maintained between the piston and the cylinder wall independently of the angularity of the rod portion of the piston. The compressor housing and cylinder assembly are made up from simple relatively light gauge steel components.

Standard valve assemblies are utilized on opposite sides of the piston to effect compression of a working iluid on each stroke of the piston. The crank pin is secured directly to the output shaft of the motor and is retained in this position by a machine screw that also functions as a counterweight.

It is to be understood that the specific constructions of the improved compressor herein disclosed and described are presented for the purpose of explanation and illustration and are not intended to indicate limits of the invention, the scope of which is defined by the following claim.

What is claimed is:

A positive displacement piston-type air compressor for attachment directly to a rotatable shaft, said compressor comprising a cylinder, a one-piece molded plastic piston in said cylinder, said piston having a spherical head por tion at one end thereof and a bore in an opposite end portion thereof extending transversely to the central axis of said cylinder and parallel to the central axis of said rotatable shaft in abutting parallel relationship, a cylindrical lcrank pin having one end portion ysecured directly to said rotatable shaft whereby the central axis of said crank pin is radially spaced from the central axis of the shaft, the other end of said crank pin being journaled directly in the bore in the opposite end portion of said piston, and an intake and an exhaust valve in said cylinder whereby rotation of said shaft effects reciprocation and articulation of said piston and induction and compression of air in said cylinder.

ReerencesvCited by the Examiner UNITED STATES PATENTS 1,257,350 2/18 Hei-le 230-172 1,470,548 i0/ 23 Spohrer 230-190 X 2,023,466 12/35 Crowley 230-172 2,515,956 7/ 50 Greenberg. 2,710,137 6/55 Arnouil 230-172 FOREIGN PATENTS 529,885 11/ 40 Great Britain.

LAURENCE v. EFNER, PrimaryV Examiner.

WARREN E. COLEMAN, Examiner, 

